But, there's another related phenomenon at work. Partisanship, it turns out, isn't always a rational choice. Rather, it's much closer to an inherited trait that we get from our families and communities.

People do not choose parties by comparing platforms and then figuring out where the nation's interests lie. Drawing on a vast range of data, these political scientists [Donald Green, Bradley Palmquist and Eric Schickler - authors of Partisan Hearts and Minds] argue that party attachment is more like attachment to a religious denomination or a social club. People have stereotypes in their heads about what Democrats are like and what Republicans are like, and they gravitate toward the party made up of people like themselves. Once they have formed an affiliation, people bend their philosophies and their perceptions of reality so they become more and more aligned with members of their political tribe.

On top of that, there's research by Bill Bishop that suggest that an ever-growing percentage of Americans are living in counties that voted 60% or better for one of the two presidential candidates. In other words, there's much less purple - and more hard-blue and hard-red counties; more "landslide counties".

Bishop blames this heightened partisanship on the proliferation of "landslide counties." He defines a landslide county as one in which the presidential nominee of one party receives at least 60 percent of the vote. In 1976, 26.8 percent of American voters lived in landslide counties. By 2000, that proportion had nearly doubled, to 45.3 percent.

What do all these numbers mean? They mean that within the universe of people who vote in presidential elections, nearly half of us are likely to be smug in our political views, while nearly one-third of us are likely to feel absolutely certain that the winds of history are at our back, rendering us utterly boorish. That's quite a market for political candidates and radio talk-show hosts to tap. Indeed, they'd be fools not to.

Can there be any other explanation, for example, at the hard-left orientation of the inner Hawthorne/Belmont area in Portland - zip code 97214 - otherwise known as "The Kremlin"? Do lefties, eco-wackos, and Naderites have a special affinity for the diagonal streets of Ladd's Addition? Is it the Ben & Jerry's on Hawthorne? Or could it be the breakfast at Bread & Ink? No, they're there because they like EACH OTHER.

So, here's what this means for those of us concerned with internet strategy for advocates and campaigns: this increasing trend makes our job easier. Internet-based "Tell a Friend" features are absolutely critical. After all, our supporter's friends are highly likely to be supporters of ours, too.

At every turn, you should be using your website to capture the attention of your supporters - and motivate them to bring their friends to the campaign.